When a person walks on flat land, the bottoms of his footwear (termed “the soles” in the following), such as a pair of shoes, positioned on the land are kept almost horizontal, and the center of gravity of his body is generally positioned right above his heels. This is the most suitable posture for a human's natural walk (termed “the natural posture” in the following).
On the contrary, when a person goes up a slope, the toes of his shoes as put on the slope are positioned more highly than the heels. Also, it is difficult to keep the natural posture while so walking. Therefore, it is necessary to keep the soles horizontally against the slope by lifting the heel of each shoe high in order to maintain the natural posture.
Conventionally, there have been a pair of mountaineering shoes installed with supporting equipment in heels of mountaineering shoes (see JP-S42-11251-Y). But, it was necessary for the equipment to be changed to correspond to each size of these shoes.
Further, there was a mountaineering fixture having an almost semicircular-shaped base, which is installed at the arched portion of the shoes (see JP-S62-196004-U1). The specification of this device states that there are advantageous effects to reduce muscle fatigue around an arch portion of a foot and leg fatigue because of supporting the body weight by the arch portions of the feet instead of the heel portions.
But, it was necessary for the equipment to be changed to correspond to each size of these shoes.
But, these almost semicircular-shaped fixtures for the mountaineering shoes have to be fixed to the shoes on a slope, or to be removed from the shoes and to be carried on flat land. Besides, in order to fix these fixtures to ordinary mountaineering shoes, it is necessary to prepare separate fixing tools.
Although it may be possible to surely reduce the muscle fatigue around an arch portion of a foot that is caused by supporting the body weight by means of the arch portions, there is a problem in that an unstable feeling, caused by shortening the distance between the two supporting points of a foot for supporting the body weight, may adversely increase the muscle fatigue of a leg, particularly, the heel and calf under the center of gravity of the body weight.
Also, shoe soles should be kept almost horizontal, particularly by lifting the toe of each sole, in descending a slope as well as in ascending a slope.
Furthermore, to walk transversely on a slope, the height of the shoe on the valley side may be adjusted so as to be higher than that of the shoe on the mountain side, and the heights of both shoes may preferably be equal.
It is an object of the present invention provide a pair of shoes having parts for keeping the natural posture despite going up or down a slope.
It is a further object of the present invention is to provide a pair of shoes with fixtures for walking on a slope and also in a flat place while maintaining the natural posture by adjusting the height of the heel, the toe, or the arched portion.